Stabilized physical developers containing ionogenic surfactants



United States Patent 0 3,157,502 STAlllLlZEl) PHYSTQAL DEVELOFERS CON- TAHN'ING IQNGGENIC SUFEACTANTS Hendrik .l'onlrer and lilornelis .iohannes Dippel, Enidhoven, Netherlands, asslgnors to North American Philips Company inc, New York, N.Y., a corporation of Delaware No Drawing. Filed 9st. 8, 1959, Ser. No. 845,698 Claims priority, application Netherlands 0st. "11, 1958 7 tlhairns. ((11. 96-49) This invention relates to developers used in the purely physical developments of photographic images and to processes employing such developers.

In the usual type of development employed in photography, the so-called chemical development, the metal in the visual photographic image is obtained by the reduction of metal ions of the Water insoluble metal compound present in the latent image in the exposed light sensitive layer.

The developing solution employed in chemical development initially does not contain any dissolved compounds of the visual image metal. l-lowever, after the chemical developer is used for a while it may contain in solution ions ofthe visual image metal.

In the purely physical development the intensification or development of the latent image is carried out by treating the latent image with a developing solution which contains a water soluble reducible metal compound and a photographic reducing agent.

In physical developing practically all of the metal in the resultant visual image is formed by the selective reduction of metal ions or complex metals anions supplied by said water soluble metal compound.

The term photographic reducing agent is to be understood herein to mean a compound which, in the dissolved state, is capable of reducing the said metal ions or complex metal anions into free metal and the activity of which in the physical developer under the conditions otherwise prevailing therein is accelerated by the presence of a photographic latent image so as to obtain a sufliciently selective deposition of metal on this latent image.

The photographic reducers which may be used in physical development are frequently similar to those which are also used in chemical development.

They often satisfy the formula wherein C represents a carbon atom, a and b each represent hydroxyl (OH) groups, amino groups or substituted amino groups (NI-l Nl-IR, NRR wherein R and R are alkyl or aryl radicals groups), n is Zero or an integer.

It is possible to distinguish three large classes of photographic reducing agents which correspond to the above general formula.

(1) That of the hydroquinone type: a and b both are OH groups. This class includes, in addition to hydroquinone itself, inter alia: pyrocatechol, pyrogallol, gallic acid and ascorbic acid.

(2) That of the aminophenol type: a is an OH-group and b is an amino group which is substituted or' not substituted. This class includes inter fl'a: oand p-aminophenol, p-methylaminophenolsulphate (metol), p-hydroxyphenylglycine (Kodurol).

(3) That of the phenylenediamine ty e: a is an amino group or a mono-substituted amino group, b is an amino group which is substituted or non-substituted. This class includes inter alia: oand p-phenylenediamine and N,N- diethyl-p-phenylenediamine.

In addition, there are some further photographic reducing agents which do not satisfy the above-mentioned for- F mula, such as l-phenyl-3-pyrazolidone (,Phenidone) and several inorganic photographic reducing agents, such as ferrous, titanous and vanadous ions, which are commonly used in the form of complex compounds, for example the ferrous-oxalate complex.

In purely physical developers, only metal ions and complex metal anions of metals which are more precious than copper, i.e., mercury, sflver, platinum, gold or paladium may be used in combination with photographic reducing agents. These metals in the instant application will be hereinafter designated as precious metals. A physical developer frequently used is, for example, a solution of silver nitrate in water to which hydroquinone, metol or pphenylenediamine has been added. In addition, some further substances are usually added to such a developer, which substances serve to increase the length of life or to control the velocity of development. These are, for example, organic acids, bulfer mixtures or substances which enter into reaction with the precious metal salt to form thereby complex metal anions.

The purely physical development hitherto employed has disadvantages which has prevented its general introduction into the photographic techniques. These disadvantages are due to the fact that physical developers, in contradistinction to chemical developers, are unstable systems due to a homogeneous reaction being liable to occur in the solution between the precious metal compound and the reducing agent in addition to the heterogeneous reaction on the latent image, whereby the latter is intensified, which homogeneous reaction then results in the spontaneous formation of metal germs in the solution and in the photographic material outside of the latent image which germs form precipitates. In addition, a spontaneous cat alyzed reduction may occur on the wall of the developing vessel and this reduction likewise gives rise to unwanted loss of metal. Once such metal germs having spontaneously been formed, their growth will compete with the deposition of the metal on the latent image obtained by the reaction of light. This spontaneous formation of the metal precipitates, of course, also takes place when the physical developer is not in use and this results in fairly rapid deterioration of such developers while isolating metal and in considerable contamination of the vessels employed. Such developers are thus uneconomical in use.

The spontaneous formation of the metal germs and resultant formation of precipitates in the photographic material outside the latent image obtained by illumination may give rise to unwanted fogging of the ultimate photographic image. The spontaneous dissociation reaction in physical developers is usually accomplished in a period of time which is not very much longer than the time required for the development of the metal latent image into a photographic visual metal image of desired opticfl density.

It is known that, in certain cases, it is possible to increase the length of life of a purely physical developer, for example, by reducing the temperature, by dilution, by decreasing the pH or by the addition of the oxidation product of the reducing agent. However, these steps cause a corresponding increase in the time of development, thus rendering such processes serviceable for the technique only in certain cases or in combination 'with additional steps. Such a step is, for example, to increase the temperature of photographic material containing an amount of such a developer suflicient for building up the image. Developers thus treated have sometimes been referred to as stabilized developers. However, they are not stabilized in the sense of the present invention in which the spontaneous separation of the precious metal from the developer is likewise materially decreased, but without at the same time considerably retarding the velocity of development- The first-mentioned kind of increase of the length of life will be referred to hereinafter as inactivation and the relevant developerswill be re- ,to an extent such that the selectivity of the precipitation .of metalon the photographic metal latent image is lost to a considerable proportion.

The drawbacks hitherto inherent in the purely phys ical development are responsible for the fact that in the photographic process based on the photo-sensitivity of silverhalide, the chemical development has been preferred,

However, there are cases that chemical development is impossible and hence physical development is the only .possibility ofintensifying the photographic latent images, since the image-producing metal, in contradistinction to the chemical development, is not yet present as a non:

soluble compound at the'area of the image. However, also in these cases in which chemical development is possible, physical development is sometimesdesirable in view of the better quality of the image, for example, in connection'with the high isolating capacity that can be obtained with it. 7

It is therefore a principal object of this invention to provide purely physical developers which are stable, that v V d a as is the case, for example, in the photographic process in which use is made of the photo-sensitivity of the socalled Eder solution and in which the light reaction prod uct is mercurous chloride. Numerous photo-sensitive compounds are also known, the light reaction product of.

which in a secondary reaction may react in the presence of moisture with mercurous-ions or Wlil'l'SllV6I-l0l15 while forming physically developable latent mercury images and latent silver images respectively. Such photo-sensitive compounds, such as aromatic diazonium compounds, diazosulphonates and diazocyanides and inorganic complex compounds, are used in a large number of processes for the manufacture of hoto'ua hie images.

is, inwhich there is littleor no precipitation of metal from thepreciousmetal compound in the developer out-' side of the'latent photographic image.

Another object of this invention is to provide purely physical developers which do not cause fogging. These and other objects of the invention will be apparent from the description that follows.

According to this'invention it has been found that the precipitation of the precious metal from the developer outside of the latent image because of the homogeneous reaction between the photographic reducing agent and the precious metal compound of the developer can be eliminated to a very large extent by the addition of one or more suitable ionic surface active agents or surfactants to the developer. As a result of the additional of these surfactants the lifeof the developer is increased at least 50% and in one case is 10,000 times that of the corresponding unstabilized developer, Example X.

The use of these ionic surfactants is based on the different behavioursof the ionic surfactants in physical development, so far as the metal precipitates spontaneously formed in the developer and the visual metal image in the photographic material are concerned; Such a selectivity is, of course, essentialto. proper action of the development stabilizers. It is extremely surprising that {the said ionic surfactants considerably delay the growth of the metal precipitatesspontaneouslyformed, without Anevertheless affecting the growth of the photographic (metal visual image in the exposed layer in a manner which is of; practical importance.

The process of the invention :may be carried out with aa ll those ,photographie materials'in which a physically -developable metal latent image may be obtained directly bl indirectly by the action of light. These photographic materials include firstof all those materials which contain a photo-sensitive compound, the light reaction prod .uct of which as such already behaves as a physically developable photographiometal latent'image, for example pound th'e' light reaction product of which as such is not materials containing silver halides as the photo-sensitive :compound. In addition, they include all those phor' .tographic'materials whichcontain a photosensitive cornibe converted-or react into a physically developable photographic metal latent image. If the light reaction prodet is. a'rnetal compound, this secondary reaction con- -sists inisolating metal particlesfrom the metal compound,

Surfactants or surface-active substances, that is to say, substances which are adsorbed at the boundary surface of two phases, are usually organic compounds having amphipathic properties. Their molecule or ion contains one or more hydrophobic and one or more hydrophilic groups,

which are bonded together either directly or via, for example, an ester, ether or amide bond. The hydrophobic groups are, for example, aliphatic carbon chains having from 8 to 18 carbon atoms with a very small affinity to the medium (water), in contradistinction to the'hydrophilic groups which have a great affinity to water. The

latter are therefore sometimes referred toas solubilising or polar groups. These may be, for example, sulphonate or pyridinium groups. The surfactants may chemically be divided into two classes:

(a) The ionic surfactants, the-"hydrophilic group of which carries the charge and which thus occur in the form of an anion, a cation or a zwitterion. Reference is then made to anion-active, cation-active and .amphoteric surfactants, respectively. 7

(b) The non-ionic surfactants, the hydrophilicgroup of which is non-ionizable.

During the establishment of the present invention, it

has been found that a favourable technical elfect in the senseipreviously described can'be obtained only when use is made of surfactants of the first-mentioned category that is the ionic surfactants. The non-ionic surfactants are thus unserviceable as development stabilizers. The

serviceable surfactants chiefly belong to the classes of the cation-active, anion-active and amphoteric micelle-pro.- ducing surfactants and to the classof the cation-active macro-molecular surfactants. V

In chemical developers, too, surfactants are sometimes used, for example of the quaternary ammonium type compounds. These may considerably speed up the development of various kinds of photographic emulsions in developers of a given composition. 7 This effect occurs when the exposed material, prior to development, is

bathed for a short time, for example, in a 0.2% solu-' tion of lanryl-pyridinium-p-toluenesulphonate. 'The problem for which the present invention provides a solution} in the physical development does not exist, however, in the chemical development and the effect of the surfactants is therefore of quitea different nature. 7

As previously mentioned, physical developers may have greatly differing compositions; they may reactin an acid,

neutral or allraline reaction and they may contain dif-; ferent compounds of precious'metals, photographic're- 7' ducing agents of difi'erent kinds and many sorts of auxiliary materials. Consequently, it willbe evident that the choice of the ionic surfactants used for obtaining "stabilization of development cannot be arbitraryf- Forfexample, those few ionic surfactantswhich produce in one i way or anothera precipitation. with one of the stituents of thephysical developer cannot beiised. Also. 7 there may be insuff cient activity by the surfactant be-q cause of the lowdissociation of the surfactan't. at the pH v of the developer concerned. I In order to determine whether a given ionic surfactant V is serviceable as-a' physicaldeveloper stabilizer under'the conditions which prevail in the physical developer chosen, the following test may be carried out.

By means of a sensitometer wedge, identical photographic metal latent images are manufactured on two foils of one of the photographic materials defined above. In covered developing vessels one of these foils is developed in a developer containing the surfactant to be tested (A), the other foil being developed in the corresponding developer from which this surfactant is omitted (B). The two foils are developed as long as is necessary for obtaining a predominantly neutral-gray copy of the wedge in developer B. in the event of the length of life of developer B being so short as to be incapable of developing into one neutral-grey copy, the development is stopped when the activityof the developer has ceased. After the development of the fiISl'. two foils has been terminated, new latent image foils identical with the firstmentioned are introduced some more times into the two developers at given intervals, the period of which may naturally be varied as a function of the length of the developers. The lengths of life of the two developers are thus approximately determined, that is to say, the times which elapse between the moment when the two developers were prepared and the moments when their developing power has disappeared almost completely. This test has at the most a semi-quantitative character, since the spontaneous formation of the metal precipitate in non-stabilized developers is naturally not reproducible with great accuracy. In order to avoid wrong conclusions which might result from the said fluctuations, one sets as a criterion of activity that the length of life of developer A with respect to that of developer B must be increased at least by 50%.

During this test it is necessary to ensure that the total amount of image metal wmch is consumed for building up the image in all the copies of the Wedge developed in one and the same developing bath, is not more than 10% of the initial potential supply of metal of this bath.

It is not possible generally to indicate the limits of the effective rmge of concentration of the surfactants. Most of the surfactants commercially sold are technical products which usually consist of a mixture of homologues which possess the same hydrophilic group and hence are not clearly defined chemically. Otherwise these technical products are, on the whole, quite serviceable without further purification, insofar as they do not show unwanted reactions in the physical developer such as formation of a deposit. However, during the establishment of the invention, it has been found that the number of carbon atoms of the lyophilic group influences the lower limit of activity when starting from pure, well defined compounds. Thus, for example, for a given physical developer it was found that for octylamine acetate this limit exists at a concentration of about 0.1 mol, for decylamine acetate at a concentration of 0.03 molar and with dodecylamine acetate at a concentration of 0.003 molar.

These results indicate that the stabilization efiect of the surfactants may be related to micelle formation by the hydrophilic ions of the surfactants at or about the small spontaneous precious metal germs from the precious metal compound thus preventing the germs from growing large enough to precipitate out of the developer solution.

With increasing concentration of the surfactant, the stabilizing effect in certain cases increases, then reaches a maxhnum and finally disappears completely. The latter is frequently accompanied by flocculation of the surfactant, in which event the activity frequently returns to an increased extent, if the fiocculated surfactant is solubilized with another ionic surfactant of the same charge or with a non-ionic surfactant. In other cases, however, a decline in activity upon increasing concentration of the surfactant could not be determined. It is not yet quite clear how all these phenomena must be interpreted. With reference to the sensitometer wedge. test described supra,

6 it is possible in all cases to determine the most active concentration or concentrations of the surfactant empirically.

During the experiments carried out in formulating this invention it was found by micro-electrophoretic measurements on the physical developers that the surfactants acted upon the electrophoretic charge of the precious metal germs. In the absence of the surfactants it was found that these previous metal germs had a charge de pending to a large extent on the other ingredients in the developer. Thus it was found that the electrophoretic charge of the spontaneous silver germs was distinctly negative in a metol-citric acid-silver nitrate developer and distinctly positive in a corresponding p-phenylene diamine-citric acid-silver nitrate developer. In corresponding alkaline developers in which sodium sulphite was employed in addition the charge on silver germ in both cases was found to be negative. The spontaneously formed germs of mercury were however, found to be positive in a hydroquinone, nitric acid, mercurous nitrate developer.

The surfactants act to increase the existing charge of the precious metal germs or to provide a new strong charge of opposite polarity on the precious metal germ depending on whether cation or anion-active surfactants are employed and whether the charge on the precious metal germ is the same or opposite to that of the hydrophilic ion released by the surfactant. By thus effecting the electrophoretic behaviour of the spontaneously formed precious metal germs in the physical developers the growth of these germs into sizes large enough to precipitate out of the solution is prevented.

The action of the hydrophilic ions on the charge of spontaneous precious metal germs involves probably the formation of micelles which as stated before prevents the growth of these germs. A strong positive charge of the germs will prevent the approach of positive metal ions, Whereas a strong negative charge may prevent transmission of electrons to the germs and approach of negative complex metal ions. hydrophilic ion of one type of charge and, in other cases, one of the other type of charge, but frequently hydro philic ions of both type of charge result in a stabilizing cfiect in a physical developer. However, the photographic test above described always gives an answer to the question Whether a given stabilizer is effective in certain kind of developer.

Nevertheless, it remains a surprising fact that the photographic metal latent image is not acted uponin the same manner as are the germs spontaneously formed, in other words, that any appreciable decrease in the velocity of development does not occur. Evidently, the position is such that formation of micelles does not occur in the latent image and that micelles formed outside latent image cannot enter it.

It has been found that most effective stabilization of the physical developer is ensured, at least if the surfactant chosen does not become inactive due to reaction with one of the constituentsof the developer, for example due to formation of a precipitate, if the surfactant is chosen to be such that the charge of the surface-active ion is opposite to the electrophoretic charge of the precious metal germs formed spontaneously in the corresponding physical developer from which the surfactant has been omitted and if the concentration of the surfactant is sufiicient 'so as to be capable of giving the spontaneous metal germs the charge of the surface-active ion.

When use is made of physical developers containing a soluble silver compound, silver germs are often spouts neously formed .in a non-stabilizeddeveloper having a stabilizcd solution have a predominantly positive charge,

Consequently, in certain cases, a

the said surfactants still permit the obtaining of a stabilizing efiect, though usually not so highly spectacular.

Aldon-active and amphoteric polymeric (macromolecular) surfactants usually have an insignificant effect as development stabilizers. On the contrary, cation-active polymeric surfactants are very serviceable more particularly when use is made of a physical developer containing a soluble silver compound.

\Vhen using an acid silver developer a particularly favourable technical effect with regard to stabilization is obtained with the aid of compounds from the following clases of cation-active surfactants:

(a) Salts of primary alkylamines, the hydrophobic allryl When use is made of acid silver developers, alkylaryl sulphonates derivatives of diphenyl also have admirable stabilizing propertiesv When using alkaline silver developers, compounds from the following classes of cation-active surfactants have a very favourable stabilizing effect:

7 '(a) Compounds, the basic, hydrophilic, nitrogen-containing group of which forms part of a pyridine ring system;

(17) Salts of primary alkylamines, the hydrophobic alkyl radical of Whichpossesses at least 8 carbon atoms, or

, mixtures of these compounds;

(c) Compounds, the basic, hydrophilic, nitrogen-containing group of which is bonded through an ether group with the hydrophobic group.

With the last-mentioned type of silver developers, compounds from the following classes of anion-active surfactants are also admirably serviceable as development stabilizers: 1

(a) Salts of sulphuric acid semieesters of aliphatic alcohols; V (b) Alkylarylsulphonates.

The knownmethod of color forming physical development by means of developers containing a soluble silver compound, in which'an image'of dye-stuff is obtained in situ with a silver image, yields the same favourable 1 results when use is made of surfactants according to the I nitrogen-containing present invention. In selecltingthe type of surfactant it is in this case also necessary to make allowance for the acid and alkaline reaction, respectively, of the developer concerned.

In physical developers containing a soluble mercury compound, the use ofanion-active stabilizers usually yields optimum results; However, if these developers re act alkaline it is also possible to obtain a favorable stabiljzjing effect with cation-active compounds and more particularly with surfactants having a basic, hydrophilic, 7 group which'forms part of a pyridine ring system. J i Avery good stabilizing effectmay be obtained in physical development by means of acid reacting developers containing soluble silver 1 compounds or mercury coinpounds if the reducing. agent employed is a compound of the hydroqiiinone type and the stabiliZ'er'is an alkylaryl sulphoriatederivedfrom diphenyl. H e V Finally, physical gold developers may best-be stabilized fbymeans of the same alklaryl'sulphonates which are de- .riva tive's of disphenyl. i i

ating this developing liquid at will by adding metal salt b 0 U As previously mentioned, a given surfactant may sometimes show a considerably smaller stabilizing effect than could be expected due to its being fiocculated under the conditions which prevail in the physical developer or.

due to its having itself unduly low solubility. 'In this case, the activity of the surfactant may be considerably increased by solubilization. This may be efiected'by means of another ionic surfactant of the same type or by means of a non-ionic surfactant.

A process is also known for obtaining metallic images in photographic material by purely physical development of photographic metal latent images, the photographic material being developed in the form of a stack of sheets in a physical developer which may be inactivated, if desired, and which contains an amount of metal salt not more than about three times as much as suffices for building up the visual images. tion, by the use of surfactants in the developers, much more beautiful results, less fogging and less contamination of the sheets due to finely-divided metal loosely deposited on them is obtained, i

In combination with known steps by which the purely physical developmentv is used in a continuousprocess,

the invention imparts to the developer properties rendering it even much more attractive for practical use.

It is possible to carry out a developing process in which the developing liquid is continuously supplied from two separate supply solutions which ares-table in themselves.

The invention may then successfully be used by adding a development stabilizer to at least one solution, so-thatf better results are obtained and the process is accomplished more economically.

If a certain amount ofphotographic' material is physically developed several times in succession in a given amount of developer whichis stabilized and possibly inactivated, the present invention also permits of regeneror an aqueous solution thereof which may be provided with a stabilizer, The process of regenerating the de-' veloper may, of course, also be carried out continuously.

In addition, the known continuous processin which the photographic material is caused to absorb an amount of inactivated developer at least suflicient for building up the images and in which the developmentis accom: plished substantially outside this supply, may be considerably improved by the use of the invention, since bymeans of stabilizers it is possible to prepare developer solutions which are durable for a much longer time than are the corresponding non-stabilized solutions'and which nevertheless exhibit a reasonable developing activity.

The invention will now be explained in detail with reference to a number of examples:

. EXAMPLES (The specified formulas are included in table.)

'I. A superficially saponified' film of cellulose acetate was sensitized by impregnating for 2 minutes with an aqueous solution containing 0.15 gram mole of the so dium salt of o-methoxy-benzendiazosulphonic acid and 0.1 gram mole of cadmium lactate per liter, followed by wiping off and drying. A piece of this film was'exposed to the light of a mercury lamp behind a, sensitorn- .eterwedge and subsequently treated with an aqueous).

solution containing 0.005 gram mole of mercurous nitrate and'0.01. 'mol of nitricacid per liter, resulting in a "mercury germ image being formed (the so-jcalled "germ image foil);

minutes in a fresh solution of 0.5 g; ofmetol, 2 g. of citrrc ac1d and0.2 g. of silver nitrate in g. of distilled water.

According to the inventhe accompanying After theformation of the germ 1 image, the foil was rinsed in distilled water. A strip of the germ image foil was physically developedafor 10 The silver germs spontaneously formed in solution were found to have a negative electrophoretic" charge. Another strip of the same germ imagefoil was developed for the same period in a fresh solution which, in addition to the said constituents, also contained 0.02 g. of the cation-active sulfactant Sapamine KW. This is the methyl sulphate of monostearylamide-ethylenetrimethyl-amine (Formula I). It was determined by electrophoretic means that the germs formed spontaneously in the solution had a very distinct positive charge. With certain intervals, which in this case were about 30 minutes, new strips of germ image foils identical with the first-mentioned were introduced into the two developing solutions and developed therein for 10 minutes.

This procedure was continued until the developing power of each solution had disappeared almost completely, while taking care that in total not more than about 10% of the silver potentially present in each of the developers at the beginning of the test was used for building up the image. The stabilized developing solution became inactive in a period of time which was three times as long (the stabilization factor) as that in which the developer without the stabilizer became inactive. A delay in the development was not established. at all in this and the following examples of stabilized physical developers, unless special statements are made to the contrary.

Instead of using the above-mentioned photo-sensitive material, it is alternatively possible in this and the corresponding subsequent examples to utilize similar materials obtained by impregnation of regenerated cellu lose film or superficially saponified cellulose-ester film with solutions of other aromatic diazosulphonates such, for example, as the sodium salt of p-methoxyor pethoxy-benzenediazosulphonic acid, the sodium salt of chloro-2-methyl-4 benzenediazosulphonic acid-l, and the sodium salt of dimethoxy-3,4 benzene-diazosulphonic acid-l, or with solutions of other photosensitive compounds from which one or more of the following molecules or ions are released by exposure: CN; CNS"; N 1 80 S0 S 05; Nl-l pyridine, thiourea or derivatives thereof.

11. A portion of a germ image foil obtained in the manner described in Example I was physically developed for 5 minutes in a fresh aqueous solution containing 0.036 gram mole of hydroquinone, 0.1 mol of nitric acid and 0.005 gram mole of mercurous nitrate per liter. It was determined by electrophoretic means that the mercury germs spontaneously forming in this solution had a positive charge. Another piece of the same foil was developed during the same time in a similar fresh solution containing, in addition, 0.2% by weight of the anionactive surfactant Aresklene-400 (Formula II), the dibutyl-O-phenylphenolsodium disulphonate. The spontaneous germs in this solution had a distinct negative charge. A portion of a germ image foil identical with the first-mentioned, after having been introduced into the developing solution without the surfactant two hours after the manufacture thereof, could be intensified no longer. On the other hand, in the developer containing the surfactant, strips of identical germ image foils could be intensified into neutral-black images in developer solutions 50 hours old when using a time of development of 5 minutes.

III. A superficially saponified foil of cellulose acetate Was sensitized by impregnating for 2 minutes in a 2% by weight solution of anthraquinonedisulphonic acid sodium-2,7, followed by wiping 0E and drying. After exposure of foils of this material to light by means of a mercury lamp, silver germ images were formed by treatment of the foils with an aqueous solution containing per liter 0.01 gram mole of silver nitrate and 0.2 gram mole of a mixture of acetic acid and sodium acetate buffer (pH=6). After this introduction of germs, the foils were rinsed in distilled water for 10 seconds.

The following physical developers were used:

(a) An aqueous solution containing 0.027 gram mole of p-phenylene diamine, 0.028 gram mole of silver nitrate and 0.95 gram mole of anhydrous sodium sulphite per liter, and (b) A similar solution containing, in addition, 0.02%

by weight of Fixanol-C (Formula 111), a cetyl pyridinium halide. The time of development was always 30 minutes.

A micro-electrophoretic test revealed that the silver germs spontaneously forming in solution a had a negative charge, whereas the spontaneous germs in solution I) had a distinct positive charge. The length of life of developer b was 50 times as long as that of developer at.

Instead of using the above-mentioned photo-sensitive material, it is alternatively possible in this and corresponding subsequent examples to utilize similar materials obtained by impregnating at least superficially hydrophilic films with solutions of other photo-sensitive compounds the light reaction product of which is capable of isolating metallic silver from solutions of silver salts, such, for example, as various naphthoquinoniand anthraquinoni compounds and certain thiazine-, azineand oxazine dyes.

lV. A superficially saponified foil of cellulose-triacetate was sensitized by impregnating for 2 minutes in an aqueous solution containing 0.4 gram mole of hydroxy-l diazo- 2 methyl-6 benzenesulphonic acid-4, 0.05 gram mole of mercurous nitrate and 0.1 gram mole of nitric acid per liter. After drying and exposure behind a sensitometer wedge with the aid of a mercury lamp, the foil was rinsed in distilled water for a short time, resulting in a mercury germ image being formed. Portions of the germ image foil thus obtained were physically developed for 10 minutes in the following freshly prepared solutions:

(a) A solution of 0.5 g. of metol, 2 g. of citric acid and 0.2 g. of silver nitrate per g. of distilled water; (17) Solution a+0.02% by weight of amine 220 nitrate (Formula V); this is hydroxyethyl-l heptadec enyl-2 imidazolinium nitrate;

(0) Solution a+0.02% by weight of amine-O acetate (Formula 1V); this is, as the Amine-220, a compound, the basic hydrophilic, nitrogen-containing group of which f rms part of an imidazoline ring system.

(d) Solution a+0.02% by weight of Sap'amine A (Formula VI); this is a compound the basic, hydrophilic, nitrogen-containing group of which is bonded via an amide bond with the hydrophobic group;

(e) Solution a+0.04% by weight of the acetateof Ethoduomene T/l3 (Formula VII); this is a ditertiary amine;

(f) Solution a+0.2% by weight of Desogene (Formula VH1); this is a quaternary ammonium compound.

Upon repeating the test in the same developer, the solution 12 to f were found to have a length of life which was from an 1 /2 to 3 times longer than that of solution a.

Instead of using the above-mentioned sensitizing solution, it is alternatively possible, for example to utilize a solution containing 3 g. of hydroxy-l diazoniurn-Z naphthalene-sulphonic acid-4,2 g. of citric acid and 4 g. of silver nitrate per 100 g. of water. Exactly the same results are obtained with germ image foils of this material.

V. A superficially saponified foil of cellulose triacetate was sensitized .by impregnating for 2 minutes in an aqueous solution containing per liter 0.07 mol of the sodium salt of p-methoxy-benzene diazosulphonic acid and 0.07 gram mole of cadmium acetate per liter, followed by drying. After a sensitometer exposure by means of a mercury lam a treatment followed for 2 seconds with an aqueous solution containing 0.005 gram mole of mercurous nitrate and 0.01 gram mole of nitric acid. per liter, so that the mercury germ image was introduced. This was followed by rinsing in distilled water for 10 seconds.

7 (a) 0.125% byweight of p-aminophenol,

by Weight of citric acid and 0.2% by weight of silver nitrate. Another portion of the same germ image foil was developed at the same time and for the same. periodin a solution prepared in the same manner and containing, in addition, 0.2% by weight of the polymeric cation-active surfactant polyvinyl-imidazol quaternized with methyl sulphate (Formula DC).

The developing tests described were repeated with strips of other germ image foils identical with the first-mentioned at intervals of 15 minutes, until the developing power of the. developers had disappeared almost completely. The developer stabilized by the polymeric surfactant was found to have a length of life three times longer than that of the non-stabilized developer. 7

. When use is made of developers which, instead of pyrogallol, contain 0.5% by weight of metol and 0.2%

by weight of N,N-dimethyl-p-phenylene diamine nitrate,

respectively, but are otherwise prepared'in a similar manner as. above, corresponding increases in the lengths of life of the relevant developers are obtained by means of the said polymeric surfactant.

VI. A strip of a germ image foil obtainedin the manner described in Example V was physically developed for 5 minutes in an aqueous solution containing per liter 0.05 gram mole'of ferrous sulphate, 0.005 mol of ferric nitrate, 0.14gram mole of citric acid'and 0.006 gram mole of silver nitrate. Three other strips of the same germ imagev foil were developed simultaneously and during the same time in solutions prepared-in a similar manner and containing, in addition, 0.02% by weight of (a) Armac 12 D (Formula X);

(b) Aerosol C 6l(American Cyanamid (30.), an ethanolated 'alkyl guanidine compound;

(c) Deodorant G 271 (Formula X I), a compound, the basic, hydrophilic, nitrogen-containing group of which forms part of a morpholine ring system;

(d) The. nitrate of .Amine-S (Formula V), a compound,

the basic, hydrophilic, nitrogen-containing group of which forms part of an imidazoline ring system.

The length of life of each developer was determined in the mannerspecified in the description of the: invention. It'was found'tha't, due to the addition of the said four cation-active surfactants, stabilization occurred b a factor whichvaried between about 2 and 15.

When working in an otherwise similar manner with developing. solutions containing 0.02% by weight'of the reducing agent phenyl-l pyrazolidon-3 (Phenidone),

2% byweight of citric acid and 0.02% by weight of silver nitrate, the said four surfactants brought about stabilization by a factor which varied between about 2 and 10.

VII. The stabilizing effect of the cation-active surfactants (aheady used in concentrations of 0.02% by weight) Sapamine KW (Formula I; see also Example I) and DeodorantG 271 (Formula XI; see also EX- ample VI) was tested in physical developers of the following compositions:

i (d) 0.25% byweight of oamiriophehbl, 2% by weight of citricfa'cid and 0.2% by; weight'oi silver nitrate :time of development: 15 minutes); 1

1% b'y weight of citric acid and 0.05% by weight'of (time of development: 10 minutes);

silver nitrate 7 0.06% by weight of N-p-hydroxyphenylgiycine" (Kodurol), 2% by weight of citric acid and 0.05% a 'by weight of silver nitrate (time of development: 7

minutes);

(g) 0.21% by weightof N,N-diethyl pphenylenediamine nitrate, 2% by weightof citric acid and 0.2% by weight of silver nitrate (time oi development: 7 minutes),

'Use was made of germ imageioils obtainedin the manner described in Examplel. Thelengths of life of the developers, stabilized and unstabilized, were determined in the manner specified in the description.

of life of the stabilized developers varied from 1.5 to 3 times that of the unstabilized developers.

VllL The stabilizing effect of the cation-active surfactants:

(a) Almac' 26 D (General Mills. Inc), a mixture of oleyl-, palmityland. stearylamino-acetates and (b) Deodorant G 271 (Formula Xi), used. in concentrations of 0.02% by weight, was tested in a physical developer containing 0.25 g. of ascorbic acid, 2 g. of citronic acid and 0.06 g..or silvernitrate per 100 gIoi water. Germ image foils obtained, for example, in

the manner described in Example l, were developed into substantially neutral-gray images within 10 min utes.

strips with identical germ images were developed during the same time in solutionsprepared in the same manner and'containing, in addition, 0.02% by weight or napamine K mula Xli) respectively. Strips with germ images produced by the first-mentioned method were developed simultaneously in the stabilized and' the'non-stabilized (c):.2% :by'weight of pyrocatechol,0.5% by weight of I developing solutions at intervals of half an hour. increase in the length of life of the developer as a result of the addition of the stabilizers was a'factor 2 to 3.

Instead or" germ images in filtration papers, such images obtained in unilaterally sensitized, white litho-paper free of' Wood could also. be'uscd with similar result.

X. Germ image foils obtained on the photosensitive I material and by means of the germ forming process described in Example llL'were used for testing the stabflh.

zation of an alkaline physical developer of the following composition: 0.38% by weight of G-enochrome-; this is the p-N,N-diethyLamino-aniline sulphite complex, 6.2% by weight of anhydrous sodiumsulphite and 0.5% by 'weight'of silver nitrate in distilled water. i The effect was tested of the followfmg. additionsof cation-active sur- 1 1 factants:

(a) 0.014% by weight ofiFixanol C (Formula lll),' a T compound, the basic, hydrophilic, nitrogen-containing group. ofwhich; forms partof 1a pyridine ring'system;

'(b) 0.014% by weight of Armac 12D (Formula X),

a primary dodecyl-amine acetate; 7 I (c) 0.014% by weight offHyamine 10 X? (Formula f XIll),'a compound, the basic; hydrOphilic' nitrQgencontaining group of which is bonded throughan ether bond with the hyd ophobic group.

n The method of testing which w'as adopted has been mentioned'in detail in the general part of thedescription. I

The time of development was always 2 minutes;

The solution which did not contain a surfactant was The length (Formula I) and Deodorant G251 (For-- The.

l3 few minutes. With the use of surfactant a, the length of life of developer was about 1 hour, with the use of surfactant [2 it was about 250 hours, and with the use of surfactant it was about 5 hours. In the case a, a small delay in development was found.

XI. With the aid of the germ image foils also used in Example X, and with the use of an alkaline physical developer containing per liter 0.014 gram mole of hydroquinone, 0.95 gram mole of anhydrous sodium sulphite and 0.0146 gram mole of silver nitrate (time of development 8 minutes), the stabilizing effect was tested of additions of 0.014% by weight of the following surfactants:

(a) Cetyl pyridinium bromide (Formula 111) wherein X=Br;

(b) Armac 12 D (Formula X);

(c) Aerosol C 61 (see Example VI).

The lengths of life of the developers containing the said surfactants were 3, 100 and 2 times, respectively, longer than the length of life of the developer without a stabilizer.

XH. A strip of a germ image foil manufactured as described in Example I was developed for 7 minutes in a freshly prepared aqueous solution containing 0.06% by weight of N-p-hydroxyphenyl glycine (Kodurol), 2% by weight of citric acid and 0.05% by weight of silver nitrate. Three other strips of the same germ image foil were developed at the same time, likewise for 7 minutm, in developers prepared in a similar manner and containing, in addition, 0.02% by weight of (a) Areskap-100 (Formula XlV); this is mono-butylphenylphenolsulphonic acid sodium; 7 (b) Aresket-300 (Formula XV), this is mono-butyldiphenylsulphonic acid sodium;

(0) Aresklene-400 (Formula 11, see also Example 11).

By repeating the above-mentioned tests with strips of new germ image foils identical with the first-mentioned after 15, 30, 60 and 120 minutes, it was found that these anion-active surfactants had a stabilizing effect corresponding to an increase in length of life by a factor 4.

XIII. The activity of Aresklene-400 (Formula II) as a development stabilizer was also tested for the following series of acid physical developers:

(a) The ascorbic acid developer of Example VIII containing 0.02% by weight of the surfactant;

(b) The o-arninophenol developer of Example Vila containing 0.2% by weight of the surfactant;

(0) The p-aminophenol developer of Example VlIe containing 0.2% by weight of the surfactant;

(d) The metol developer of Example 1 containing with 0.2% by weight of the surfactant;

(:2) The phenyl-1-pyrazolidon-3 developer of Example VI containing 0.2% of the surfactant;

(f) The o-phenylene diamine-developer of the following composition:

0.2% by weight of o-phenylene diamine nitrate,

2% by weight of citric acid,

0.2% by weight of silver nitrate and 0.2% by weight of surfactant (time of development:

7 minutes);

(g) The diethyl-p-phenylene diamine developer of Example Vllg containin 0.02% by weight of the surfactant;

(h) The ferrous-developer of Example VI, likewise containing 0.02% by weight of the surfactant.

The lengths of lifev of all these developers were from 2 to 8' times as long as that of the corresponding non stabilized developers. The development of germ foils in these developers was free of fogging effect, whereas the development in the non-stabilized developers sometimes involved troublesome fogging.

)GV. The stabilizing effect of a plurality of anionactive surfactants belonging to the classes of the salts of i4 sulphuric acid semi-esters of aliphatic alcohols and of the alkylaryl sulphonates was tested for the following alkaline physical developers:

(a) The alkaline hydroquinone developer of Example XI; (12) The alkaline p-methylaminophenolsulphate (metol) developer of the composition:

Metol: 0.014 molar Anhydrous sodium sulphite: 0.95 molar Silver nitrate: 0.0146 molar Time of development: 8 minutes (0) The alkaline N,N diethylamino anilinesulphite (Genochrome) developer of the compositon:

Genochrome: 0.0157 molar Anhydrous sodium sulphite: 0.95 molar Silver nitrate: 0.0295 molar Time of development: 2 minutes The following surfactants were used:

(1) 0.014% by weight of Lissapol C (Formula XVI) in the developers at, b and c. Stabilization factor: 4 to 10;

(2) 0.15% by weight of Areskap- (Formula XIV, see also Example XII) in developer a. Stabilization factor: 2;

(3) 0.14% by weight of AI'BSKGi- OO (Formula XV, see also Example XII) in developer at. Stabilization factor: 2;

(4) 0.14% by weight of Aresklene-44 (Formula H, see also Example 11) in the developers a and b; 0.014% by weight of Aresklene-400 in developer 0. Stabilization factor: 5 to 20.

(5) 0.014% by weight of Nekal BX, an alkylaryl sulphonate, in the developers at and b. Stabilization factor: 3 to 8.

f, in the last-mentioned case, one of the alkylaryl sulphonates Invadin N or Perminal BX instead of Nekal BX was used, stabilizing etfects were obtained which were likewise very acceptable.

XV. With the aid of germ image foils obtained in the manner described in Example 111, tests were carried out on an acid developer and an alkaline color forming physical developer, in order to determine to what extent the lengths of life of these developers can be increased by the use of ionic surfactants.

The compositions and the times of development of the relevant developers were as follows:

(a) 0.2% by weight of p-N,N-dimethylamine-aniline nitrate, 2% by weight of citric acid, 0.2% by weight of silver nitrate, and 0.08% by weight of a-naphthol (coloring component) in distilled water. Time of development: 1.5 minutes. i

(b) The Genochrome-developer of Example X, to which 0.11% by weight of phenyl-l methyl-3 yrazolon-5 was added as a color forming component. Time of development: 6 minutes.

In developer a, the following cation-active surfactants produced the stabilizing effects mentioned therewith:

0.02% by weight of Armac 1213 (Formula X), stabilization factor: 20;

0.02% by weight of Sapamine KW (Formula I),

stabilization factor: 5;

0.02% by weight of the nitrate of Amine-S (Formula V), stabilization factor: 5;

In developer b, the stabilization effects, obtained with several cat'on-active and anion-active compounds were as follows:

(Formula XIII),

15 0.014% by weight of Lissapol C (Formula XVI),

stabilization factor: 2; 0.014% by Weight of Aresklene-400 (Formula II),

stabilization factor: 2; 0.014% by weight of Invadin N (see Example XIV),

stabilization factor: 2.

XVI. In a similar manner and with the aid of similar germ image foils as in the receding example the stabilizing effect of a plurality of anion-active surfactants was tested for several acid and alkaline mercury developers.

Compositions of the developer without stabilizers:

(a) Acid hydroquinone developer: see Example H; (b) Acid metol developer:

p-Methylaminophenolsulphate Nitric acid: 0.1 molar Mercurous nitrate: 0.005 molar Time of development: minutes Acid N,N-dimethyl pphenylene diamine-developer: N,N-dirnethyl p phenylene diamine-nitrate: 0.01

molar Lactic acid: 0.02 molar Mercurous nitrate: 0.001 molar Time of development: 3 minutes Alkaline hydroquinone-developer:

Hydroquinone: 0.03 molar Anhydrous sodium sulphite: 0.45 molar Mercuric bromide: 0.0145 molar Time of development: minutes 7 Alkaline metol developer: p-Methylamino phenolsulphate (metol): 0.03 molar Anhydrous sodiumsulphite: 0.45 molar Mercuric bromide: 0.0145 molar Time of development: 10 minutes (metol) 0.012 molar XVII. Some further tests were carried out to determine the stabilizing efiect of cation-active surfactants in alkalinemercury developers. These developers, apart from the surfactant,- had the following compositions:

( The alkaline hydroquinone developer of Example XVId;

7' (b) .The alkaline metol developer of Example XVIe;

(c) The alkaline N,N-dimethyl-p-phenylene diamine The surfactants employed and the results Were as follows:

Ooncentra- 1 tion in the Used in Stabiliza- Surfaetant developer, developer tion percent by factor weight Armac 12D (Formula X) 0. 02 6 Getylpyridinium. bromide (For- 0. 02 12 mula Ill) wherein X =Br. 0. 02 8 Hyamine 10X (Formula XII I) 0. O2 2 Aerosol 061 (see Example V1.) 0.02 3 Deodorant G 271 (Formula XI) 0. 02 2 Nitvrate of Amine-S (Formula 0.02 3

L Quaternary S 1 0. OZ 2 Quaternary S in a quaternary imidazolinium chloride, derived from amine-S (Formula IV) having a molecular weight of 455. V

For these tests use was made of photo-sensitive mate- 7 rial manufactured by impregnating a superficially-saponilied foil of cellulose acetate for 2 minutes in a solution containing 5 gms. of mercuric chloride, 5 gms. of ferric ammonium oxalate and 2.5'gms. of ammonium oxalate per 100 gnis. of distilled water.

XVIII. Use was made of acid developers of the hyroquinone type, which are derivatives of diphenyl produced very special effects dependent upon concentration, as may appear from comparison of the results given below and those of Example 11 on the one hand with those of the Examples X11 and XIII, on the other hand.

Developers:

(a) Acid hydroquinone developer of Example VIIa; (1)) Acid pyrogallol developer of Example Vllb; (0) Acid pyrocatechol developer of Example Vllc.

XEX. Germ image foils obtained in the'manner described in Example I, after having been rinsed in distilled'water for 1 minute, were treated with 0.8 molar ammonia and again rinsed in distilled water. Subsequently, the physical development took placefor 8' minutes in solutions containing per 100 g. of distilled water: I l

(f) Alkaline N,N-dirnethy1 p phenylene' diamine-developer:

N,N dimethyl-p-phenylenediamine nitrate: 0.004- molar Potassium thiocyanate: 0.008 molar Borax: 0.05 molar 4 Mercuric bromide: 0.0017 'molar v Time of development: 1.5 minutes The table below gives an impression of'the increased length of life of several developers due to the addition of the specified anion-active substances.

Coneentra- V tion in the Used in Stabiliza- Surfactent developer, developer tion percent 1by factor weigh 0.02 50 Lissapol-C (Formula XVI) 0.02 2 {I 0. 02 5 0. 02 1o 0.02 20 Arcsklene-OO (Formulall) 0.02 100 0.02 s 0. 02, 4 0.02 250 2 10 n 7,, 2 10 Perrmnal Bk 40 0.02 4

(a) 0.33 g. of potassium gold chloride 7 1.3 g. of oxalic acid :(b) As a and, in addition, 0.2 g. of Aresklene-400 (Formula II) J The length or" life of developer b was at least twice. V

as long as thatof developer a. I

XX. A strip of a germ image foil obtained in the manner described in'Example I, was physically developed for 10 minutes in a freshly prepared solution'containing I 0.5 g. of metol, 2 g. of citric acid and 0.2 gjof silver nitrate per g. of distilled water. Another strip of the same germ image foilwas developed-in a similar solution which contained, in addition, 0.02% by weight of Alamac 26D (Example Villa) and 0.02% byweight of Sapamine KW (Formula I). Alamac 26Dffpro- 1 duced flocculation if added alone to the said metol-citric acid-silver nitrate developer. Howeven'this cation-active surfactant was. solubilized by theFSapamine KW which is likewise cation-active. The stabilizing efiect became .manife'st by an increase'in the length of life ofltlle de in wmch the allrylaryl sulphonates 17 veloper by a factor of 40. Sapamine KW alone produced an increase by a factor 3 only, whereas Alamac 26D in the flocculated state did not produce any elfect.

XXI. In the tests now following, use was made of germ image foils obtained by exposure of a film specially made for electron microscopy with an emulsion of silver halide. After physical development, the foils were fixed in an aqueous solution containing 5% by weight of sodium thiosulphate and 0.5% by Weight of sodium hydroxide, and rinsed.

Efforts were made to stabilize the metol-citric acidsilver nitrate-developer of the preceding example wi the use of 0.02% by weight of Armac 12D (Formula X). However flocculation then occurred in the developer. Such flocculation could be avoided by adding, in addition, 0.02% by weight of the non-ionogenous compound Lissapol-N, which as such did not produce any stabilizing efiect. However, the combination of the two surfactants produced a stabilizing eflect of a factor 10.

XXII. A strip of a germ image foil manufactured in the manner described in Example I, was developed for 5 minutes in a freshly prepared aqueous solution containing 0.06% by Weight of N-p-hydroxyphenyl glycine, 2% by weight of citric acid and 0.1% by weight of silver nitrate. Two other strips of the same germ image foil were developed at the same time, likewise for 5 minutes, in similar fresh solutions containing, in addition, 0.098% by weight of pure dodecyl-amine acetate and 0.098% by Weight of pure dodecylamine acetate together with 0.0087% by weight of pure decylamine acetate, respectively. The said surfactants were obtained in the pure state by distilling the free impure amines at decreased pressure in an apparatus having a high separating capacity and subsequently adding the calculated amount of acetic acid to the constantly-boiling fraction. The above-mentioned development tests were repeated in the same solutions after 10, 20, 40, 80 and 160 minutes. In the solution containing only the pure dodecylamine acetate as a Surfactant, flocculation was found to occur after 10 to 30 minutes. The stabilizing efiect in this solution was comparatively low and non-reproducible, that is to say, dependent upon the time after which the flocculation was largely accomplished. In the solution containing both dodecyl acetate and decylamine acetate, flocculation still occurred after several hours and the stabilizing effect was greater than a factor 10, whereas decylamine, if it was present in the developer as the only surfactant in the concentration used herein, still had not perceptible influence upon stabilization.

XXIII. A strip of a germ image foil obtained in the manner described in Example 1H, was physically developed in the alkaline hydroquinone developer of Example XI which was freshly prepared and non-stabilized. Another strip of the same germ image foil was developed in the corresponding stabilized developer containing as the stabilizer 0.014% by weight of the amphoteric compound N-lauryl (aminosulpho) fl-aminobutyric acid (Desil). After every 15 minutes, new germ image foils identical with the first-mentioned were developed in the two developers. The stabilization factor under the described conditions was about 5.

Table Formula Trade Name Source I [C sH37%?-NC2H4N(CE3)31(S04011 Sapamine KW Oiba.

II CaHs-Ce OH Areslrlene 400 Monsanto Chem. Co.

(SO3N&)2

111 (O5H5NHC1 Hu)X (X=Gl or Br) Fixanol O Lilgh and Co. Imperial 01 N-OHQ IV CH3(CH2)11 C For Amine O, n=16 Mel. weight=355 Amine O For Amine S, n=16 M01. weight=360 Amine S i Chem- B is a substituent having a comparatively low molecular weight.)

no on no on X 90% Oz2H25NHz.CH3C O OH Amine 220 nitrateu" Union Carbide and Carbon Corp Saparnine A Ciba.

Ethoduomene T/l3. Armour and Co.

Desogen Geigy.

Polyvinylimidazol Bad. Anilin u. Sodafabr.

Armac 12L Armour and Co.

While we have described our invention in connection with specific embodiments and applications, other modifications thereof will be readily apparent to those skilled in this art Without departing from the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A stabilized photographic physical developer comprising an acid aqueous solution of a Water soluble silver salt reducible to metallic silver, a photographic reducing agent for reducing said silver salt to silver; and at least one cationic surfactant said cationic surfactant being selected from the group consisting of water soluble salts of primary alkylamines wherein the aikyl moiety is hydrophobic and contains at least 8 carbon atoms, cetyl pyridinium halides, the methyl sulphate of monostearylamidoethylene-trimethyl-arnine, imidazoiidine derivatives containing an alkyl of 16 carbon atoms attached to a carbon atom of the heterocyclic nucleus and a lower alkyl attached to a nitrogen of the heterocyclic nucleus, tolylundecylammonium compounds, benzyldimethyl {2{2- [4(Cl,l,3,3 tetramethylbutyl) tolyloxy]-ethoxy}ethyl} ammonium compounds, N-lauryl (aminosulpho) ,B-aminobutyric acid, trimethyl-Z-oleoylamino-ethyl ammonium compounds, trimethyl-2-stearylamino-ethyl ammonium compounds and morpholine compounds of the formula ene diamine and a mixture of ferrous and ferric ions for reducing said silver salt to silver and at least one cationic TableContinued Formula Trade Name Source B CH:CH2 XI V N O (SO C H Dedorant G 271 Atlas Powder Co.

CzH5 GHr-CHg (R=OmH 01 1131, O Haa, S 8E 013113 and alkyl residues with 20-24 carbon atoms.)

Cie as CHPOHQ XII O (SOAOZHE) Deodorant G 251 Atlas Powder Co.

2 5 GHFCH? 7 CH CH:

XIII (CHa)aCOHz-COsHaO C2H4-O CzH4N(CH )zCHa Hyamine 10X Rohm and Haas.

but CaH .Cl.H O

cine

XIV C(iH5CGH2 OH Areskap Monsanto Chem. Co.

SOsNa XV I?I Ia Aresket 300....-. Monsanto Chem. Co.

XVI CHa(CHg)7C=C(CH2)7CH2SOaNa Lissapol G Imp. Chem. Ind.

surfactant'said cationic surfactant being selected from the group consisting of water soluble salts of primary alkyl amines wherein the alkyl moiety is hydrophobic and contains at least 8 carbon atoms, cetyl pyridinium halides, the methyl sulphate of monostearylamidoethylene-trimethyl-amine, imidazolidine derivatives containing an alkyl of 16 carbon atoms attached to a carbon atom of the heterocyclic nucleus and a lower alkyl attached to a nitrogen of the heterocyclic nucleus, tolylundecylammoniurn' compounds, benzyldimethyl {2{2-[4(Cl,1,3,3-tetramethylbutyl) tolyloxy] ethoxy}ethyl} ammonium compounds, N-lauryl (aminosulpho) [i-aminobutyric acid,

3. A stabilized photographic physical developer com prising an acid aqueoussolution of a Water soluble, sil-j ver salt reducible to metallic silver, a photographic reducing agent for reducing said'silver salt to silver and at least one anionic surfactant, said anionic surfactant being selected from the group consisting'of alkylarylsulfonates and sulfonated alkyl alcohols, said surfactant being present in an amount sufiicient to increase the life of the developer at least 50% when compared to the life of an identical developer without said surfactant.

4. A stabilized photographic physicaldevelop'er comprising an acid aqueous solution of a water soluble silver salt reducible to metallic silver, a photographic reducing agent selected from the group consisting of N- methylaminophenyl sulfate, pyrogallol, N,N-dimethyl-pphenyl diamine, phenyl-1-pyrazolidone-3, hydroquinone, pyrocatechol, o-aminophenol, -aminophenol, ascorbic acid, N p-hydroxyphenylglycine, N-N-diethyl-p-phenyl ene diamine and a mixture of ferrous and ferric ions for reducing said silver salt to silver and at least one anionic 23 surfactant, sa d anionic surfactant being selected from the group consisting of alkylarylsulfonates and sulfonated alkyl alcohols, said surfactant being present in an amount sufiicient to increase the life of the developer at least 50% when compared to the life of an identical developer without said surfactant.

5. A stabilized photographic physical developer comprising an alkalinic aqueous solution of a water soluble silver salt reducible to metallic silver, a photographic reducing agent for reducing said silver salt to silver and at least one cationic surfactant selected from the group consisting of the water soluble salts of cetylpyridinium halides, primary alkylamines wherein the alkyl moiety is hydrophobic and contains at least 8 carbon atoms, benzylmethyl{2{ [4(Cl,1,3,3 tetramethylbutyl) tolyloxy]ethoxy}ethyl} ammonium compounds and ethanolated alkyl compounds, said surfactant being present in an amount sufficient to increase the life of the developer at least 50% when compared to the life of an identical developer without said surfactant.

6. A stabilized photographic physical developer comprising an alkalinic aqueous solution of a Water soluble silver salt reducible to metallic silver, a photographic reducing agent selected from the group consisting of p-phenylene-diamine, p-N,N-diethylamino-auiline sulfite, hydroquinone and N-methylarninophenolsulphate and an alkylaryl sulfonate surfactant said surfactant being present in an amount sufficient to increase the life of-the developer at least 50% when compared to the life of an identical developer without said surfactant.

7. A stabilized photographic physical developer comprising an alkalinic aqueous solution or" a Water soluble silver salt reducible to metallic silver a photographic reducing agent for reducing said silver salt to silver and at least one anionic surfactant selected from the group consisting of alkylaryl sulfonates and Water soluble salts of sulfuric acid semi-esters of aliphatic alcohols, said surfactant being present in an amount sufiicient to increase the life of the developer at least when compared to the life of an identical developer Without said surfactant.

References Cited in the file of this patent UNITED STATES PATENTS 2,000,353 Schaefier May 7, 1935 2,197,809 McQueen Apr. 23, 1940 2,220,929 Kirby Nov. 13, 1940 2,648,604 Welliver et al Aug. 11, 1953 2,662,822 Land Dec. 15, 1953 2,868,643 Jonge et al. Jan. 13, -9

FOREIGN PATENTS 157,182 Australia June 28, 1951 167,781 Australia June 17, 1954 OTHER REFERENCES 'lasstone, 3.: Physical Chemistry (2d ed), page 1205, D. Van Nostrand, New York (1954).

Henney and Dudley: Handbook of Photography, pages 346, 373, Whit-tlesey (McGraw-Hill), New York (1939).

CERTIFIeATE o con Hendrick Jonker et al'Q It is hereby certified that'error appears in the' above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 12, for "clases" read classes line 14, strike out "alkyl"; columns 17 and 18, in the Table,' Formula "I" should appear as shown below instead of asin the patent:

C H |(iINCL H N(CH )i ($0 011 0 H a same table, under the column headed "Trade Name" opposite formula X, for "Armac 12L" read Armac 12D column 20, line 71, for "phenyl diamine" read phenylene diamine column 2l line 15, for "benzy1methyl{2 [4" read henzyldimethyl ;.;2{2- [4 Signed and sealed this 3rd day of August 1965,

(SEAL) Attest:

ERNEST W, SWIDER EDWARD JO BRENNER Attesting Officer Cormnissiioner:of Patents: 7 

1. A STABILIZED PHOTOGRAPHIC PHYSICAL DEVELOPER COMPRISING AN ACID AQUEOUS SOLUTION OF A WATER SOLUBLE SILVER SALT REDUCIBLE TO METALLIC SILVER, A PHTOTGRAPHIC REDUCING AGENT FOR REDUCING SAID SILVER SALT TO SILVER AND AT LEAST ONE CATIONIC SURFACTANT SAID CATIONIC SURFACTANT BEING SELECTED FROM THE GROUP CONSISTING OF WATER SOLUBLE SALTS OF PRIMARY ALKYLAMINES WHEREIN THE ALKYL MOIETY IS HYDROPHOBIC AND CONTAINS AT LEAST 8 CARBON ATOMS, CETYL PYRIDINIUM HALIDES, THE METHYL SULPHATE OF MONOSTEARYLAMIDOETHLENE-TRIMETHYL-AMINE, IMIDAZOLIDINE DERIVATIVES CONTAINING AN ALKYL OF 16 CARBONATOMS ATTACHED TO A CARBON ATOM OF THE HETEROCYCLIC NUCLEUS AND A LOWER ALKYL ATTACHED TO A NITROGEN OF THE HETEROCYCLIC NUCLEUS, TOLYLUNDECYLAMMONIUM COMPOUNDS, BENZYLDIMETHYL (2(2(4(CL,1,3,3 - TETRAMETHYLBUTYL) TOLYLOXY)-ETHOXY)ETHYL) AMMONIUM COMPOUNDS, N-LAURYL (AMINOSULPHO) B-AMINOBUTYRIC ACID, TRIMETHYL-2-OLEOYLAMINO-ETHYL AMMONIUM COMPOUNDS, TRIMETHYL-2-STEARYLAMINO-ETHYL AMMONIUM COMPOUNDS AND MORPHOLINE COMPOUNDS OF THE FORMULA 